The long-term objectives of this proposal are: 1) to evaluate the current practice of mandatory hospitalization for observation only following two specific types of injury; minimal closed head injury and blunt abdominal trauma, and 2) to develop practice guidelines that could reliably exclude significant injuries without hospitalization. Attainments of these objectives would allow patients to be safely discharged from the emergency department without hospital admission and result in a better utilization of health care resources for these types of injuries. Institution of such practice guidelines could substantially reduce the annual aggregate health care cost for these injuries. Hospital admission for observation is the current standard of practice for patients who have sustained minimal closed head injuries or blunt abdominal trauma and who do not require emergent operation, even if they have undergone diagnostic studies that excluded the presence of an injury. The rationale behind this medical practice is that even if no significant injuries are discovered when a patient is first evaluated, in-hospital observation will identify any delayed injury which appears allowing rapid treatment to be instituted. This approach was formulated prior to and has lagged behind recent improvements in the diagnostic imaging of the trauma victim and the development of dedicated trauma systems and has not been re-evaluated in light of these advancements in trauma care technology. The specific aims of this project are: AIM 1: to obtain high quality prospective data that will allow precise estimates of the false negative rates for the various components of the emergency department evaluation for the following two specific types of injury; a) Minimal Head Injury (MHI), defined by a history of transient loss of consciousness, a Glasgow Coma Scale score of more than 14 and non-focal neurological examination and, b) Minor Abdominal Trauma that does not require emergent operation. AIM 2: To determine whether in-patient hospitalization for observation improves substantially the diagnostic results afforded by improvements in diagnostic technologies now available. AIM 3: To make recommendations regarding the optimal diagnostic evaluation for the two types of injury studied and to disseminate that information to health care professionals involved in trauma care. To accomplish these aims patients meeting the entry criteria will undergo a standardized emergency department diagnostic work-up for each injury type followed by in-patient admission for observation (current standard of medical care). AIM 1: The confidence intervals for the false negative rates for each feature of the emergency department evaluation will be determined. The diagnostic work-up will include a thorough physical examination accompanied by cranial computed tomography (CT) in the head injured, and diagnostic ultrasonography and abdominal CT in patients with abdominal injuries. All patients will be monitored prospectively in the hospital to assess the incidence and significance of any missed injuries. AIM 2: Upon completion of these studies, it is anticipated that a diagnostic algorithm for each injury will be constructed which could identify the group of patients without significant injury following minor trauma. AIM 3: Findings from these studies will be synthesized into recommendations regarding the optimal work-up and the disposition of patients who have sustained the minimal head and abdominal injury. This information will be disseminated to national trauma organizations and through publications in peer-reviewed journals.